Grinding-bur.



H. G. MOOULLOGH. GRINDING BUR.

Patented May 21, 1912.

UNITED STATES PATENT onnion.

HARRY G. MCCULLOCH, OF FREEPORT, ILLINOIS, ASSIGNOR TO THE STOVE-R MANU- FACTURING COMPANY, OF FREEPOR'I, ILLINOIS, A CORPORATION OF ILLINOIS.

GRINDING-BUR.

To all whom it may concern:

Be it known that I, I'IARRY Gr. MoCUL- LOCH, a citizen of the United States, residing at Freeport, in the county of Stephenson and State of Illinois, have invented certain new and useful Improvements in Grinding-Burs, of which the following is a specification.

This invention relates to grinding burs for feed mills and aims to produce a bur which can be employed for grinding grain or'feed of various degrees of fineness ranging from a very coarse to a very fine grain, thus eliminating the necessity of keeping on hand three sets of burs, one adapted for coarse, another for medium and the third for fine grades of feed as has heretofore been necessary.

The invention will perhaps be best understood by referring to the following description in connection with the accompanying drawings, in which Figure 1 illustrates a face view of one embodiment of my invention. Figs. 2, 8 and 1 are sectional views of the grinding bur shown in Fig. 1 taken on the lines 2-2; S-3; and M, respectively, and showing a companion bur in operative re lation to the bur shown in Fig. 1. Figs. 5 and 6 are sectional views of the grinding and cutting portions respectively of the teeth taken on the lines 5--5 and 6-6 of Fig. 1, Fig. 5 showing a sectional view of the cutting portion of the teeth, and Fig. 6 a like view of the grinding portion.

In feed grinding mills as is well known to those familiar with the art, the actual grinding operation is performed by a set of grinding burs, one of which is statioir arily mounted and the other revolubly mounted; the grinding faces of the two burs being disposed adjacent each other and adjusted to the required proximity to produce meal or feed of the required fineness. In the type of mill in which the burs constituting the subject matter of the resent invention are adapted to be used, tie stationary and. revolving burs are practically identical in construction, consequently I have deemed it necessary to show and describe in the present application but one of these burs.

From the drawings it will be observed that the grinding bur, which is designated generally by the reference character 5, 1s

Patented May 21, 1912.

Serial No 611,709.

circular in form and providedrwith a central orifice or aperture to permit the bur to be slipped over the grinding shaft or the cone of the mill and to either be fastened to the stationary or the revolving bur plate in any well known or approved manner. The face of the bur comprises a flat portion 6 adJacent its periphery disposed in a plane parallel with the plane of rotation of the bur, and a tapered portion 7 disposed at an angle to the flat portion so that an inclined throat 8 opening toward the centers of the burs, as shown in Figs. 2, 3 and 4, is formed to permit the entrance of the feed between the burs. The face of each bur is provided with a series of outstanding grinding teeth spaced at regular intervals around its periphery and extending across or partially across the face of the bur at a slight inclinatron to the radii of the bur. The outer end portions 9 of all the teeth positioned upon the flat portion 6 of the bur constitute the bases of the teeth. All of-these bases are of the same height and present flat tops or grinding faces disposed in a plane parallel with the flat portion 6 of the bur face. The long grinding teeth 10 which extend entirely across the face of the bur are higher at their inner ends than at their bases so as to provide a right line grinding face extending entirely across the bur in a plane parallel with the plane of rotation of the bur. From Fig. 4 it will be evident that the grinding faces of the long teeth 10 on the adjacent burs are disposed in parallelism throughout their length. These high and long teeth running close together serve to cut the particles of feed which have been previously crushed and broken to a certain extent, so that the fed particles when discharged areof a uniform size and grade. The forward face of each of the teeth 10 is disposed substantially at right angles to the face of the bur to present a sharp shearing edge adapted to cooperate with-similar shearing edges on the companion teeth of the other bur, while the rear face 10' of each of the long teeth is inclined or beveled across the tapered portion of the bur to support and strengthen the tooth and also to provide a sharp edge at the top of this portion of the tooth.

Between each of the teeth 10 there is arranged a plurality of short teeth 11 the grinding faces of which beyond their bases 9 are disposed substantially parallel with the tapered portion 7 of the bur. These short teeth extend but partially across the tapered portion of the plate and permit the larger particles of grain or feed to enter the throat 8 to a point to where they are engaged and preliminarily crushed by these teeth. Between the teeth 11 there are arranged the intermediate teeth 12 which are of a length intermediate the short teeth 11 and the long teeth 10. These teeth 12, as will be observed from Fig. 3, are higher, 2'. 6., project farther outwardly from the face of the bur than the teeth 11, but their grinding faces also are disposed parallel with the tapered portion of the bur permitting the entrance of particles therebetween through the throat 8. In the present instance I have shown the center one of the intermediate teeth 12 as longer than the others, and while this length is not essential it has been found to give very desirable results owing to the fact that the grain entering the throat between the spaced teeth 10 is more evenly distributed between the various teeth than would be the case if all of the teeth 12 were of the same length. The front faces of each of the teeth 11 and 12 are preferably vertically disposed with respect to the face of the bur while their rear faces are inclined to afford strength and rigidity to the teeth and to provide sharp cutting edges similarly to the teeth 10. It will be observed that all of the teeth with which the bur is equipped have a flat topped pase portion and a sharp edged inner por- The bur is preferably provided with a plurality of countersunk holes 13 to receive fastening screws or bolts by means of which the burs are fastened to the bur plates.

The grinding burs which have heretofore been employed and which were provided with grinding teeth all of the same height, have caused the grinding shaft to exert a considerable amount of longitudinal thrust upon its bearings owing to the tendency of the burs to separate when large particles of grain or other feed were caught and crushed between the faces of the teeth. This end thrust is very materially reduced by the employment of the burs disclosed in the present application by reason of the fact that the coarse grain or other particles enter the throat between the burs and are first cut by the short teeth, then by the intermediate teeth and subsequently reduced to the required fineness by the long high teeth, in each instance reduction insize of the particles being effected by a cutting action be tween the perpendicular faces of the oppositely revolving teeth rather than by a crushing action such as has been customary heretofore. It will be obvious that a cutting of the particles will not cause as much longitudinal thrust on the grinding shaft as would be caused by a crushing action. By making the teeth of various lengths and heights a large throat is provided which will permit the entrance of large sized kernels of grain or other feed particles as well as the smaller grains. This construction of the bur enables coarse, medium and fine feed to be ground by the same burs, thus eliminating the necessity of keeping on hand three different sets of burs as has heretofore been necessary; one for coarse, one for medium and one for fine feed.

In the present invention I have illustrated the teeth as arranged on the bur in groups of eight but I do not wish to be limited to the exact arrangement of the teeth shownas it will be obvious that the number of the teeth may be increased or diminished and their arrangement varied if found desirable.

. I claim:

1. A grinding bur provided with a series of teeth, each having a flat grinding portion adjacent the periphery of the bur and a sharp edged cutting portion extended 1nwardly from said flat portion, said flat portions being disposed in a common plane.

2. A grinding bur provided with. a series of teeth, all of said teeth having flat topped I, 7

base portions, the grinding faces of which are disposed in the same plane, and all of said teeth having sharp edged portions projecting inwardly from the base portion, the sharpened portions of some of said teeth being higher than the sharpened portlons of other teeth.

3. A. circular grinding bur havinga tapered face terminating in a flat portion adjacent the periphery of the bur and a series of teeth having grinding and cutting portions arranged upon the face of the bur, the faces of the grinding portions of all the teeth lying in a plane parallel with the flat portion of said bur, the cutting surfaces of some of the teeth throughout their length extending in a right line from the grinding portion thereof, and the cutting faces of the remaining teeth tapering from a right line along the tapered portion of the face of said bur.

4t. A grinding bur having a flat outer portion and a tapered inner portion, said bur being provided with a series of grinding teeth, the grinding faces of some of said teeth being disposed throughout their length in a plane parallel with the flat portion of said bur, and the grinding faces of the remaining teeth being disposed throughout a part of their length in a plane parallel with the tapered portion of said bur all of said teeth being disposed tangentially to a common circle.

5. A grinding bur having a fiat outer portion adjacent its outer periphery, and a tapered portion disposed within said outer portion, a series of teeth on the face of said bur,

the outer portions of all the teeth being provided with flat grinding surfaces lying in a plane parallel to the plane of the outer portion of the bur, and the inner portions of said teeth being cut away to form cutting edges, some of said teeth extending across the face of the bur in a right line, and the others deflected parallel to the tapered portion of the bur.

6. A grinding bur provided With a series of teeth, each having a flat inding portion adjacent the periphery an parallel to the face of the bur, and a sharp-edged cutting portion extending inwardly from the said flat portion.

HARRY G. McGULLOCH.

Witnesses R. M. BENNETHUM, J. F. DITTMAN.

Copies 01 this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. G. 

